std::is_enum Template in C++

Last Updated : 19 Nov, 2018
The std::is_enum template of C++ STL is used to check whether the given type is enum or not. It returns a boolean value showing the same. Syntax: 
template <class T> struct is_enum;
Parameter: This template accepts single parameter T (Trait class) to check whether T is a enumeration type or not. Return Value: This template returns a boolean value as shown below:
  • True: if the type is a enumeration.
  • False: if the type is a non-enumeration.
Below programs illustrate the std::is_enum template in C++: Program 1:: CPP 
// C++ program to illustrate
// is_enum template

#include <iostream>
#include <type_traits>
using namespace std;

class GFG1 {
};
enum class GFG2 { var1,
                  var2,
                  var3,
                  var4
};

// Driver code
int main()
{
    cout << boolalpha;
    cout << "is_enum:" << endl;
    cout << "GFG1: "
         << is_enum<GFG1>::value << endl;
    cout << "GFG2: "
         << is_enum<GFG2>::value << endl;

    return 0;
}
Output: 
is_enum:
GFG1: false
GFG2: true
Program 2:: CPP 
// C++ program to illustrate
// is_enum template

#include <iostream>
#include <type_traits>
using namespace std;

class GFG1 {
};

enum class GFG2 : int {};

// Driver code
int main()
{
    cout << boolalpha;
    cout << "is_enum:" << endl;
    cout << "GFG1: "
         << is_enum<GFG1>::value << '\n';
    cout << "GFG2: "
         << is_enum<GFG2>::value << '\n';
    cout << "int: "
         << is_enum<int>::value << '\n';
    return 0;
}
Output: 
is_enum:
GFG1: false
GFG2: true
int: false
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